Add daemon configuration

Signed-off-by: Jean Wasilewski <henyxia@revs0.com>

README.md

@@ -50,6 +50,15 @@ Docker Compose installation options.
       - user1
       - user2
 
+Docker daemon [configuration options](https://docs.docker.com/engine/reference/commandline/dockerd/#daemon-configuration-file) which will be used to create the `daemon.json` file.
+
+    docker_daemon_options:
+      storage-driver: "zfs"
+      bip: "100.64.0.1/24"
+      default-address-pools:
+        - base: "100.64.0.0/15"
+          size: 24
+
 A list of system users to be added to the `docker` group (so they can use Docker on the server).
 
 ## Use with Ansible (and `docker` Python library)

tasks/main.yml

@@ -11,6 +11,16 @@
     state: "{{ docker_package_state }}"
   notify: restart docker
 
+- name: Add daemon configration
+  copy:
+    dest: /etc/docker/daemon.json
+    mode: 0600
+    owner: root
+    group: root
+    content: "{{ docker_daemon_options | to_nice_json }}"
+  when: docker_daemon_options is defined
+  notify: restart docker
+
 # TODO: Remove this shim once 18.09.1 or later is released.
 - import_tasks: docker-1809-shim.yml
   when: ansible_service_mgr == 'systemd'